hi Gurpreet Singh ! has this been a recent complain,or it's been like this since long?? please ensure he gets fresh before sleeping.. avoid serving heavy, oily stuff in dinner. avoid junk food or refined flour based recipes. make sure he has enough fruits , vegetables duirng the day and maintain hydration. also please keep a watch on hygiene and make sure he doesn't eat mud, or any other non edible items. please ensure he is not allergic to any of the food items that he eats.. if it persists consult ur doc. try and add heeng and ajwain to food. here is a blog u would find useful.
https://www.parentune.com/parent-blog/बच्चों-के-लिए-अजवाइन-के-कुछ-चमत्कारिक-गुण/2920?ptref=sa0l000ytzt0294